Rheostat



m". -o'g SAN BA1/34m" CALIFORNIA.

Be it known, that 1, Joux PARKIN,' citizen of .the United specification.

ply this demandthat I have devised my present invention in whichtheelementsare reduced to tlie.. least o ssible number and rreatest possible simp icity. `It will vbefunilerstood that it may be suitably employed in other instances where a resistance varying device is needed.

The invention possesses other features of advantage, some of which, with the fo4A oing, will be set forth in the following e scription of the preferred form of myinventiqn which is illustrated in the drawings accompanying and forming part of the specification. lt is to be understood that I do not limit myself to the showing made by the said drawings and description, as I may adopt variations of the preferred form with in the scope of my invention as set forth in the claims.

Referring to the drawings: Figure 1 is an elevation of the rheostat,

the panel on which it is mounted being 40 shown is section. Fig. 2 is a rear elevation of the knob detached from the panel. Fig. 3 is an elevation of a modified form of my device.

My rheostat comprises a knob 2 of bakelite or other non-conducting material mounted upon a shaft 3. A fiange 4 integral with orixed tothe shaft forms the inner face of. the knob and a button 6 or 'similar device integral with or fixed to the flan e or shaft provides means for uniting the nob to the flange and shaft. Preferably the shaft, fiange and button are formed in one piece of hard bra ss, and the knob molded upon the button and flange as shown in Fig. l. 55 The outer` end of the knob is enlarged by n., ay States; and a resident of San Rafael county-of Marin,-.and State'ffl of California, lave invented anew amlnf-ie-n-A fnl Rheostat,. of 'which-the followingiis-u v.

" 't the coil lis f `end 'of'the wird tlirou' l 11, openin 'onf the inner' 'slope ofthe knob 65.

v:r:- anfefjwvhich iskni'irled n'tiie edge to'v provi e *a ing'erT'grip; andA just insidethe" lflan' isformed an annular groove about'J the itb an ptedto'sezitfaresistance element 8 \vhicll:con\'ei1iently'`1ay beformedof ajfo helical coillof resistarice-wine.,A (lne end 9 of lsecuredtothemfiterial of the knob", and-togdo-"this lpreferfto hook the gh''fi small aperture ttorn of the. groove; They other passes" through anapex-'l niertre 11, fand' "is con- 1f y'Ito the peri her 'o`f` he d-.a ut' 70 The shaft is' of such lengthas* 'to ex- Z tend tlirough'-the `panel 1li/on which the dei ,vice is mounted@sindterminates{in a. threaded end upon whichf'twonuts 17 are"threaded. 7 5,`

of the panel is.-a""pring 18 mijustal'ilytemy sioned. ythe nuts. The spring retains the knob resiliently against" the panel. Interposed between the spring and the panel is s. Contact plate 19 which is obviously in elec` trical contact with -the shaft 3. One side 21 of the circuit inwhich the rheostat is. used2 is connected to the contact plate. The other side 22 of the circuit is connected to 585. bolt 23 by 'nuts 24.l The bolt passes through the paneiand secures r diy thereagainst the spring arm 26 whic extends toward the knob and resiliently `enga the resistance element 8. A pin 27 em ded in the 'lmob between the ends 9 and 12 Vof the resistunce element acts as a stop by engagement with the arm 26 to determine the extreme sitions of the rheostat. From the above 1t will be understood that'the resistance of the circuit 21 and 22 may be varied b turning the knob, the entire resistance elbment being in circuit when the knob is turned to one extreme, and practically the entire resistance being cut out at theothor extreme. i v

In Fig. 3 I have shown a modified form-of my rheostat in which the groove 31 for the resistance element is formed in the inside lateral face of the'flo. the arm 26 is suitabl' facilitate contact wit nient.

I claim:

1. A variable resistance device comprising 1) 'l 7. In this case nt at the end to the resistance ele- I a conductor fixed 'dlsposed in said a rotatabl.)y mounted knob havi a-peri heryadaptmg it for digital con rol, an n variable 'resistance element circnlnrly disposed about said knob rotation therewith. r

2. variable resistance device comprising a ,rota ably mounted knob havin e' peri hery adaptingv it for-digital cont ,it varia le resistance e ement ciroula1'ly"tlisp0sed about said knob, a conductor on said knob fol connecting saidelement to one side of a. \cir cuit, and a conductor fixed adjacent said knob and eli'dably engaging said element for connecting it' with the other side of said circuit.

3. l A variable resistan a rotntabl mounted shaft of conducting nialerial, a mob of non-conducting material lixed on said shaft. und formed with u periphe'ry adapting it for digiml control, a helical coil of resistance wire circularly disposed about, said knob and havin one of its ends electrically connected to said Shaft, adjacent said knob and slidably engaging said coil, and a conductor Slidnbl)r engaging said shaft.

4. variable resistance device comprising a knob having an annular groove therein and formed with n periphery adapting it for digital control, a variable resistance element groove, a conductor on said knob for connecting said element to one side of a circuit, and

and fixed thereon for vsaid sha device comprising a conductor fixed adjacent" said knob and slidably engaging said ele-' manier ment for connecting it with theother eide of seid circuit. l

5. A variable resistance device comprisi a panel of nomconducting material, eshii of conducting material rotatably mounted in said panel, a. knob an annuler 40 havin groove therein fixed on seid safina variable resistance element `disposed in said ve and electrically connected at one en with ft, an arm of 'conducting material fixed on said pan'el and resiliently engagin 45 said element, a plate of conductin materii on the rear of said panel in slidabe engage- `mentwith said sh'aft, and' a. sprin interposed between said plate an'd said s at'to retain the knob in sition. a 6. A variable resistance device com rising a knob having an annular groove t erein, a variable resistance element dis osed in said groove; n conductor on said ob for connecting said element to one side of a circnit. n conductor fixed adjacent seid knob and slidably engngin said element for connecting it with the ot er side o said circuit, and a stop pin disposed in said knob between the ends of said element and adapted to engage said conductor to limit the rota-.f tion ofsaid knob.

ln testiinony `whereof, I have hereunto set. niv hand a-tbnn Francisco, California, this 5th dayof Augnstflill.4 ,JOHN PARKIN, JR. Inpreseno I C. S. EvANZ" 

